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Images and multimedia
Intermediate
Dynamic Webcam ImageBy Laurent KempéStreaming Dynamic Images from your webcam into your web pages. |
C#, Windows, .NET 1.0, ASP.NET, Visual Studio, Dev
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This project presents the way to dynamically generate a picture with C# and
ASP.NET. Basically a browser points to your page and gets back a picture
grabbed on your webcam.
You will be able to access your webcam by placing a HTML IMG tag on your
webpage. The picture at the top is an example of usage.
To be able to use the webcam you need to register with regsvr32 the COM Dll
CamServer.dll in the 'COM Component' directory.
The first thing to do to get a picture from an ASP.NET page is to determine the
MIME file type that the file will handle. In our case the MIME type is JPEG. So
we define in the ContentType of the Page:
<%@ Page Language="c#" ContentType="image/jpeg" %>We also need to specify at the top of the page the namespace that will be used:
<%@ Import Namespace="System" %>
<%@ Import Namespace="System.IO" %>
<%@ Import Namespace="System.Drawing" %>
<%@ Import Namespace="System.Drawing.Drawing2D" %>
<%@ Import Namespace="System.Drawing.Imaging" %>
<%@ Import Namespace="System.Net" %>
Then comes the code that will grab the image from the wbecam and returns it to
the client:
<script language="C#" runat="server">
protected void Page_Load(object sender, EventArgs e)
{
//Jpeg compression quality
short nQuality = 45;
//Shout a picture from my webcam
CAMSERVERLib.Camera cam = new CAMSERVERLib.CameraClass();
byte[] picture = (byte[])cam.GrabFrame( nQuality );
//Add the hour to the jpeg picture
MemoryStream ms = new MemoryStream( picture );
Bitmap bmp = new Bitmap( ms );
Graphics g = Graphics.FromImage( bmp );
string strDate = DateTime.Now.ToLongDateString() + " - " +
DateTime.Now.ToLongTimeString();
StringFormat drawFormat = new StringFormat();
drawFormat.Alignment = StringAlignment.Center;
g.DrawString( strDate,
new Font( FontFamily.GenericSansSerif, 12 ),
new SolidBrush( Color.Black ),
new RectangleF( 1,1,320,240 ),
drawFormat
);
g.DrawString( strDate,
new Font( FontFamily.GenericSansSerif, 12 ),
new SolidBrush( Color.White ),
new RectangleF( 0,0,320,240 ),
drawFormat
);
//Get codecs
ImageCodecInfo[] icf = ImageCodecInfo.GetImageEncoders();
EncoderParameters encps = new EncoderParameters( 1 );
EncoderParameter encp = new EncoderParameter( System.Drawing.Imaging.Encoder.Quality,
(long) nQuality );
//Set quality
encps.Param[0] = encp;
bmp.Save( Response.OutputStream, icf[1], encps );
g.Dispose();
bmp.Dispose();
}
</script>
In the code there is nothing new, compared to the other articles. We get a jpeg
picture grabbed by the webcam using COM Interop. We add the hour and the little
difference is that the image stream is saved to Response.OutputStream
.
You may reference the ASP.NET page has a normal jpeg picture:
<img src="http://XXX/WebcamPicture/WebForm1.aspx" width="320" height="240"/>
or in a ASP:Image
control.
This opens lots of possibilities in the creation of dynamic graphics. For example you may create dynamic charts linked to database values returned has a normal graphic in a presentation page. You may also make easily a visit counter for your pages...
| Version 1.00 |
June 14, 2002
First release. |
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Last Updated: 24 Jun 2002 Editor: Chris Maunder |
Copyright 2002 by Laurent Kempé Everything else Copyright © CodeProject, 1999-2009 Web10 | Advertise on the Code Project |
